Augmented reality system eye relief adjustment mechanism

ABSTRACT

A head mounted display (HMD) may comprise an adjustable crown band, a crown band circumference adjusting mechanism coupled to the adjustable crown band and configured to adjust a crown band circumference to releasably secure the crown band to the user&#39;s crown, an armature including left and right arms, each of the left and right arms mounted at a respective proximal end to corresponding left and right HMD attachment structures, a display mounted at left and right sides to respective distal ends of the left and right arms, and an eye relief distance adjustment mechanism configured to move the left and right arms in a timed manner toward and away from the crown band along a substantially linear path, to thereby adjust an eye relief distance from the display to an eye of a the user when the crown band is fitted on the crown of the user.

BACKGROUND

Augmented or virtual reality systems exist for simulating virtualenvironments within which a user may be immersed. Displays such asheads-up displays (HUDs), head-mounted displays (HMDs), and the like,may be utilized to display the virtual environment. In order to maintainuser comfort and proper alignment of the display relative to the eyes ofthe user in the immersive environment, an HMD may have to accommodatevarious head sizes and various eye relief distances. Conventional HMDsemploy pivoting hinge and plate mechanisms to adjust eye relief forvarious user head sizes, which can be bulky, cumbersome to manipulate,and may not accommodate a broad range of user head sizes and eye reliefdistances. Failure to accommodate a user's head size can result in theHMD being too tight and causing discomfort, or too loose and movingrelative to the user's head during use, negatively impacting the user'sexperience. Failure to maintain proper eye relief distance can adverselyimpact the user's ability to properly perceive the augmented realityelements displayed on the display of the HMD.

SUMMARY

According to one aspect of this disclosure, a head mounted display (HMD)to be worn by a user comprises an adjustable crown band, a crown bandcircumference adjusting mechanism coupled to the adjustable crown bandand configured to adjust a circumference of the crown band to releasablysecure the crown band to the crown of the user, an armature including aleft arm and a right arm, each of the left and the right arm mounted ata respective proximal end to corresponding left and right attachmentstructures on the HMD, a display mounted at left and right sides torespective distal ends of the left and right arms, and an eye reliefdistance adjustment mechanism configured to move the left and right armsin a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance fromthe display to an eye of a user when the crown band is fitted on thecrown of the user.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an illustrative example of a crown portion ofan HMD device including a crown band circumference adjustment mechanismand an eye relief distance adjustment mechanism in accordance with afirst embodiment of the present disclosure.

FIG. 2 is a rear perspective view of the HMD device of FIG. 1.

FIG. 3 is a cross-sectional view of the HMD device of FIG. 1 taken atsection 3-3.

FIG. 4 is a posterior view of the HMD device of FIG. 1

FIG. 5 is a plan view of an illustrative example of an HMD device inaccordance with a second embodiment of the present disclosure.

FIG. 6 is a posterior perspective view of the HMD device of FIG. 5.

FIG. 7 is a side view of the HMD device of FIG. 5.

FIG. 8 is a cross-sectional perspective view of HMD device of FIG. 5.

FIG. 9 is an anterior view of the HMD device of FIG. 5

FIG. 10 is a posterior perspective view of an illustrative example of anHMD device in accordance with a third embodiment of the presentdisclosure.

FIG. 11 is a side view of HMD device of FIG. 10.

FIG. 12 is a plan view of HMD device of FIG. 10

FIG. 13 is a cross-sectional view of HMD device of FIG. 10 taken atsection

FIG. 14 is a posterior perspective view of an illustrative example of anHMD device in accordance with a fourth embodiment of the presentdisclosure.

FIG. 14A is a partial anterior exploded perspective view of the HMDdevice of FIG. 14.

FIG. 15 is a side view of the HMD device of FIG. 14.

FIG. 16 is a posterior view of the HMD device of FIG. 14.

FIG. 17 is a partial cross-sectional view of the HMD device of FIG. 14taken at section 17-17.

FIG. 18 is a cross-sectional view of the HMD device of FIG. 14 taken atsection 18-18.

FIG. 18A is an exploded perspective view of an example posterior housingof the HMD device of FIG. 14.

FIG. 19 is a perspective view of an illustrative example of an HMDdevice in accordance with a fifth embodiment of the present disclosure.

FIG. 20 is a posterior perspective view of the HMD device of FIG. 19.

FIG. 21 is a partial side perspective view of the HMD device of FIG. 19.

FIG. 22 is a partial side perspective view of the HMD device of FIG. 19.

FIG. 23 is a side view of HMD device of FIG. 19.

FIG. 24 is an anterior perspective view of an illustrative example of anHMD in accordance with a sixth embodiment of the present disclosure.

FIG. 25 is a partial side perspective view of the HMD device of FIG. 24.

FIG. 26 is a partial side perspective view of the HMD device of FIG. 24.

FIG. 27 is a perspective view of the HMD device of FIG. 24.

FIG. 28 is a side view of the HMD device of FIG. 24.

FIG. 29 is a posterior perspective view of an illustrative example of anHMD device in accordance with a seventh embodiment of the presentdisclosure.

FIG. 30 is a cross-sectional view of the HMD device of FIG. 29 taken atsection 30-30.

FIG. 31 is an anterior perspective view of the HMD device of FIG. 29.

FIG. 32 is a side view of an eye relief band of the HMD device of FIG.29.

FIG. 33 is a side view of the HMD device of FIG. 29.

FIG. 34 is a perspective view of an illustrative example of an HMDdevice in accordance with an eighth embodiment.

FIG. 35 is a partial side perspective view of the HMD device of FIG. 34.

FIG. 36 is a side view of the HMD device of FIG. 34.

FIG. 37 is a perspective view of an illustrative example of a completeHMD device, including the crown portion of the HMD device and an HMDdisplay.

FIG. 38 is a perspective view of an armature of an HMD coupled to an HMDdisplay.

FIG. 39 is an isolated perspective view of an armature.

DETAILED DESCRIPTION

The subject matter of this disclosure is now described by way of exampleand with reference to certain illustrated embodiments. Components thatmay be substantially similar in one or more embodiments are identifiedcoordinately. It will be noted, however, that components identifiedcoordinately may also differ to some degree.

Referring now to FIGS. 1-4, various views of an HMD device 100 accordingto a first embodiment of the present disclosure are illustrated. Toaddress the challenges discussed above, an HMD may include HMD device100 to be worn by a user, the HMD device 100 comprising an adjustablecrown band 110. The circumference of the adjustable crown band 110 maybe adjusted by a crown band circumference adjusting mechanism coupled tothe adjustable crown band, the crown band circumference adjustingmechanism configured to adjust a circumference of the crown band toreleasably secure the crown band to the crown of the user. In theexample embodiment shown in FIGS. 1-4, the crown band circumferenceadjusting mechanism comprises the adjustable crown band 110, knob 120,housing 130, and crown racks 118. By rotating the knob 120 in a first orsecond direction, crown racks 118 may be driven to either increase ordecrease the circumference of the adjustable crown band 110,respectively. In this way, the crown band circumference adjustingmechanism may facilitate user adjustment of the HMD and thereby reduce arisk of the HMD being too tight and causing discomfort, or too loose andmoving relative to the user's head during use, and negatively impactingthe user's experience.

As shown in FIGS. 37-39, the HMD may further comprise an armature 3750,including a left arm 3752 and a right arm 3754, each of the left and theright arm mounted at a respective proximal end 3758 to correspondingleft and right attachment structures 140 on the HMD device 100.Attachment structures 140 may comprise a plurality of mounting holes towhich armature 3750 may be mounted. In other examples, attachmentstructures may comprise hooks, clips, rivets, screw, and otherattachment mechanisms. The armature supports and affixes a displayassembly 3790 to the HMD device 100, the display assembly 3790 mountedat left and right sides to respective distal ends 3756 of the left andright arms 3752, 3754.

The HMD device 100 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 1-4, the eye relief distance adjustment mechanism comprises leftand right eye relief bands 150 and 152, knob 120, housing 130, eyerelief racks 156, attachment structures 140, and sliding structures 116.By rotating knob 120 in a first or second direction, eye relief racks156 may be driven to move the attachment structures (along with thearmature 3750 and display assembly 3790) in a timed manner anteriorly orposteriorly, respectively, along the distal surface of the adjustablecrown band 110 to increase or decrease an eye relief distance 3792,respectively. In this way, the eye relief distance adjustment mechanismmay facilitate adjusting eye relief distance of the HMD to increase auser's ability to properly perceive the augmented reality elementsdisplayed on the display of the HMD, while achieving a comfortable fitto the user's head size via the crown band circumference adjustmentmechanism.

Also depicted in FIGS. 1 and 2 are axes 102 illustrating anterior,posterior, left, and right directions, and axes 103 illustrating dorsal,ventral, anterior, posterior, left, and right directions. Left and rightends of the adjustable crown band 110 extend posteriorly from left andright sides, respectively, and wrap around a user's crown at a posteriorside, passing through and overlapping inside a housing 130 mounted at aposterior end of the HMD device 100. In some examples, the left andright ends of the adjustable crown band 110 may overlap and extendbeyond the housing 130 such that left and right ends of the adjustablecrown band 110 extend to posterior right and left sides, respectively ofthe HMD device 100.

The adjustable crown band 110 also extends anteriorly from left andright sides, respectively, and wraps around a user's crown at ananterior side when the HMD device 100 is worn by the user. At theanterior side, adjustable crown band 110 may comprise a hinged structure106 positioned at an anterior side of the HMD device 100, the hingedstructure 106 including fasteners 104. The hinged structure 106 maypivot to enlarge and contract an angle 108 between a left and rightanterior ends of the adjustable crown band 110 to aid in the HMD device100 easily and comfortably fitting a wide range of crown circumferencesat an anterior side of the HMD device 100. In this way, both the hingedstructure 106 and the inherent flexibility of the crown band 110 may aidin easily and comfortably fitting a wide range of crown circumferencesat an anterior side of the HMD device 100. Fasteners 104 may serve torestrict an angle 108 and/or to reinforce a hinged structure 106 and tostrengthen the hinged structure 106 and/or the adjustable crown band 110thereat. In some examples, left and right anterior ends 107 of theadjustable crown band 110 may comprise a continuous length of crown bandinstead of the hinged structure 106, and the inherent flexibility of thecrown band 110 may aid in easily and comfortably fitting a wide range ofcrown circumferences at an anterior side of the HMD device 100 withoutthe hinged structure 106.

Furthermore, adjustable crown band 110 may further comprise a pluralityof cutouts 114 distributed throughout a length of the adjustable crownband 110. Cutouts 114 may aid in reducing the weight and in increasingthe flexibility of the adjustable crown band 110, thereby increasing fitand comfort. Cutouts 113 in the left and right eye relief bands 150, 152may aid in reducing the weight and in increasing the flexibility of theleft and right eye relief bands 150, 152, thereby increasing fit andcomfort. Cutouts 113 and 114 are shown as triangular, however, the shapeof cutouts 113 and 114 may be rectangular, circular, polygonal, and thelike.

Left and right eye relief bands 150, 152 flexibly wrap around theadjustable crown band extending from left and right anterior eye reliefband ends 157, 158 at left and right sides to a posterior side of theHMD device 100, passing through and overlapping inside the housing 130.In some examples, left and right posterior ends 153, 154 of the left andright eye relief bands 150, 152 may overlap and extend beyond thehousing 130 such that left and right ends 153, 154 of the left and righteye relief bands 150, 152 extend to posterior right and left sides,respectively of the HMD device 100.

Housing 130 may comprise a crown rack housing 132 and an eye relief rackhousing 134. As such, left and right ends of the adjustable crown bandmay pass through and overlap inside the crown rack housing 132,separately from left and right eye relief bands 150, 152, which may passthrough and overlap inside the eye relief rack housing 134. In this way,interference between the adjustable crown band 110 and the left andright eye relief bands 150, 152 as they pass through the housing 130 isreduced. Housing 130 further comprises a knob 120, and a curved housingposterior support band 136, as will be further described below.

Left and anterior eye relief band ends 157, 158 may slidably engage withand be retained adjacent to a distal surface of the adjustable crownband 110 by a plurality of sliding structures 116 mounted at left andright distal sides of the adjustable crown band 110. Sliding structures116 may extend distally relative to the adjustable crown band 110 andthe user's crown, from both dorsal and ventral edges of the adjustablecrown band 110, greater than a thickness of the left and right eyerelief bands 150, 152. In the embodiment of FIGS. 1-4, the slidingstructures 116 comprise a plurality of clips; however in other exampleembodiments the sliding structures 116 may comprise loops, bands, rails,or other structures that guide and facilitate sliding of the eye reliefbands 150, 152 adjacent to a distal surface of the adjustable crown band110. Furthermore, tips 117 of the sliding structures 116 may extend inventral and dorsal direction from dorsal and ventral edges,respectively, of the adjustable crown band 110, to retain left and righteye relief bands 150, 152 adjacent and wrapped around an outer surfaceof the adjustable crown band 110. In particular, a distance between tips117 in the dorsal-ventral direction may be less than a width of the eyerelief racks 156 in the dorsal-ventral direction. A number of thesliding structures 116, and a spacing between each of the slidingstructures 116 may be predetermined to smooth sliding of the eye reliefbands 150, 152 along the distal surface of the adjustable crown band 110and to reduce snagging of the eye relief bands 150, 152 on the edges ofthe sliding structures 116. For example, the sliding structures mayextend over a length of the adjustable crown band 110 on the left andright sides and the spacing between each individual sliding structuremay be small enough to facilitate sliding of the left and right eyerelief bands 150, 152 directly adjacent to the adjustable crown band110. Furthermore, sliding structures 116 may each comprise tips 117,including beveled distal edges, to increase user comfort while graspingthe adjustable crown band 110, for example, to don or doff the HMDdevice 100.

Turning now to FIGS. 3 and 4, a partial cross-sectional view taken atsection 3-3 and a posterior view, respectively, of the HMD device 100are illustrated. As shown in FIG. 3, left and right ends of theadjustable crown band 110 may each include a crown rack 118 passingthrough and overlapping inside crown rack housing 132. Furthermore, leftand right posterior ends 153, 154 of the left and right eye relief bands150, 152 may each include an eye relief rack 112 passing through andoverlapping inside eye relief rack housing 134. Crown racks 118 and eyerelief racks 112 may be engaged to a pinion 122, and pinion 122 may bemounted to the housing 130 and rotatably coupled to knob 120 via aratchet 124. Ratchet 124 may rotationally lock the pinion 122 in one orboth directions. For example, ratchet 124 may rotationally lock pinion122 in the crown tightening direction (e.g., where rotation of thepinion 122 reduces a crown circumference). As shown in FIG. 3, eyerelief racks 112 may be coupled to pinion 126. Pinion 126 is mounted tothe housing 130 and may be rotatably coupled to knob 120. As such, whenknob 120 is rotated, pinion 122 engages crown racks 118 to adjust alength of the left and right crown racks passing through the firsthousing, thereby adjusting a circumference of the crown band in a timedmanner. Furthermore, pinion 126 may not be rotatably coupled to pinion122 so that pinion 126 may be rotated independently from pinion 122.Further still, translation of eye relief racks 112 and rotation ofpinion 126 may be restrained by frictional forces between the eye reliefracks 112 and attachment structures 116, between the eye relief racks112 and the housing 130, between the eye relief racks 112 themselves,between the pinion 126 and the eye relief racks 112, and the like. Thesefrictional forces may be overcome when knob 120 is rotated, therebycausing pinion 126 to engage eye relief racks 112 to adjust a length ofthe left and right eye relief racks passing through the housing 130,thereby adjusting the anterior-posterior positioning of the attachmentstructures 140 in a timed manner with the adjustment of the crowncircumference. These frictional forces may also be overcome by applyinga pushing or pulling force to the display posteriorly or anteriorlyrelative to a user's eye's to adjust an eye relief distance.

Because the display assembly 3790 is mounted to armature 3750, which ismounted at attachment structures 140, rotating the knob 120 may adjustthe eye relief distance 3792. Rotating knob 120 in a first direction maydecrease a length of the left and right crown racks passing through thehousing to increase a circumference of the adjustable crown band 110,while rotating knob 120 in a second direction may increase a length ofthe left and right crown racks passing through the housing to decrease acircumference of the adjustable crown band 110. Furthermore, rotatingknob 120 in a first direction may decrease a length of the left andright eye relief racks passing through the housing to increase an eyerelief distance 3792, while rotating knob 120 in a second direction mayincrease a length of the left and right eye relief racks passing throughthe housing to decrease an eye relief distance 3792.

Housing 130 may further comprise retaining screw 128 and washer 129 forsecuring knob 120, and housing posterior head support band 136 forcomfortably supporting the housing 130 against the posterior surface ofthe user's crown. Housing posterior head support band 136 may be widerthan a width of the eye relief bands 150, 152 and adjustable crown band110 to reduce a pressure against a posterior surface of the user'scrown, and may comprise a plurality of cutouts 138 which may reduce theweight of the HMD, and may impart increased flexibility to the housingposterior head support band 136. Housing fasteners 131 may securehousing 130 around the crown racks 118 and eye relief racks 112.

Sliding structures 116 positioned on the distal side of both dorsal andventral edges of the adjustable crown band 110 guide the eye reliefbands 150, 152 to translate along a substantially linear path in adirection aligned with the adjustable crown band 110. In addition toadjusting eye relief by rotation of knob 120, a pushing force towards ora pulling force away from the user's eyes applied to the displayassembly 3790 mounted to armature 3750, which is mounted to HMD device100 at attachment structures 140, may decrease or increase the eyerelief distance, respectively. In this way, the eye relief bands 150,152, may be slid across the surface of the adjustable crown band 110, asthey are held in position by sliding structures 116. The friction forcebetween the eye relief bands 150,152 and adjustable crown band 110 andthe sliding structures 116 may influence the pushing and pulling forcesrequired to adjust the eye relief distance. Furthermore, adjusting theeye relief distance adjustment mechanism and the crown circumferenceadjustment mechanism to achieve a particular eye relief distance mayinclude adjusting the eye relief bands, accounting for the adjustment ofthe adjustable crown band 110, since both the crown band and eye reliefbands may be grounded to the pinion 122 of the rear housing. In otherwords, when the circumference of the adjustable crown band 110 isadjusted via rotating knob 120, the eye relief bands 150, 152 may alsobe adjusted via application of a pushing and/or pulling force to thedisplay assembly 3790 to maintain an eye relief distance 3792 whileachieving a comfortable fit to the user's crown.

The adjustable crown band 110, and the left and right eye relief bands150, 152 may be flexible to enable bending and flexing thereof to followthe curvature of a user's crown so that a close and comfortable fit ofthe HMD to the user's crown can be achieved. At least one or more ofcutouts 113, 114, structural features of sliding structures 116 (e.g.,spacing therebetween), cutout 138, curved housing posterior support band136, and the material of construction thereof may thus substantiallyimpart flexibility and elasticity to the HMD device 100 so that a closeand comfortable fit to a broad range of user crown sizes may beachieved.

Turning now to FIGS. 5-6, plan and rear perspective views areillustrated of a second example embodiment for an HMD device 200,including axes 202, 203 indicating dorsal, ventral, anterior, posterior,left, and right directions. An HMD may include HMD device 200 to be wornby a user, the HMD device 200 comprising an adjustable crown band 210.The circumference of the adjustable crown band 210 may be adjusted by acrown band circumference adjusting mechanism coupled to the adjustablecrown band, the crown band circumference adjusting mechanism configuredto adjust a circumference of the crown band to releasably secure thecrown band to the crown of the user. In the example embodiment shown inFIGS. 5-9, the crown band circumference adjusting mechanism comprisesthe adjustable crown band 210, knob 220, housing 230, and crown racks216. By rotating the knob 220 in a first or second direction, crownracks 216 may be driven to either increase or decrease the circumferenceof the adjustable crown band 210, respectively. In this way, the crownband circumference adjusting mechanism may facilitate user adjustment ofthe HMD and thereby reduce a risk of the HMD being too tight and causingdiscomfort, or too loose and moving relative to the user's head duringuse, and negatively impacting the user's experience.

The HMD device 200 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 5-9, the eye relief distance adjustment mechanism comprises leftand right eye relief bands 250 and 252, knob 220, housing 230, eyerelief racks 280, 282, attachment structures 140, and sliding structures116. By applying a pulling force toward or a pushing force away from auser's eyes, eye relief racks 280, 282 may be driven to move theattachment structures (along with the armature 3750 and display assembly3790) in a timed manner anteriorly or posteriorly, respectively, alongthe distal surface of the adjustable crown band 210 to increase ordecrease an eye relief distance 3792, respectively. In this way, the eyerelief distance adjustment mechanism may facilitate adjusting eye reliefdistance of the HMD to increase a user's ability to properly perceivethe augmented reality elements displayed on the display of the HMD,while achieving a comfortable fit to the user's head size via the crownband circumference adjustment mechanism.

HMD device 200 includes left and right adjustable crown bands 210, 212that extend posteriorly from left and right sides and wrap around theposterior of a user's crown when the HMD device 200 is worn on theuser's head. At the posterior side of the HMD device 200, ends of theleft and right adjustable crown bands 210, 212 may pass through andoverlap inside a crown rack housing 230 mounted at a posterior end ofthe HMD device 200. In some examples, left and right adjustable crownbands 210, 212 may overlap and extend beyond right and left sides of thecrown rack housing 230, respectively. Ends of the left and rightadjustable crown bands 210, 212 may each include a crown rack 216mounted thereto. Crown racks 216 may pass through and overlap insidecrown rack housing 230 and may be engaged to a crown rack pinion 292.The crown rack pinion 292 may be rotatably coupled to posterior knob220. Accordingly, rotating posterior knob 220 engages crown rack pinion292, which in turn engages crown racks 216 to adjust a crowncircumference. Rotating knob 220 in a first direction may decrease alength of the left and right crown racks passing through the housing toincrease a crown circumference, while rotating knob 220 in a seconddirection may increase a length of the left and right crown rackspassing through the housing to decrease a crown circumference.

The anterior crown band 214 may wrap around an anterior of a user'scrown when the HMD device 200 is worn on the user's head. Posterior endsof the anterior crown band 214 may be attached at left and right sidesof HMD device 200 via side fasteners 231 to anterior ends of the leftand right adjustable crown bands 210, 212. Anterior crown band 214 mayinclude sliding structures 116, and eye relief rack housing 270 mountedat an anterior end of HMD device 200. As crown circumference isincreased, the position of attachment structures 140 may be moved in ananterior direction co-linear with the anterior crown band 214. As crowncircumference is decreased, the position of attachment structures 140may be moved in a posterior direction co-linear with the anterior crownband 214. Further still, when crown circumference is decreased, a radiusof curvature of the anterior crown band 214 a radius of curvature of theleft and right adjustable crown bands 210, 212 may decrease as theanterior crown band 214 and the left and right adjustable crown bands210, 212 are increasingly bent to conform to a smaller crowncircumference. Further still, when crown circumference is increased, aradius of curvature of the anterior crown band 214 a radius of curvatureof the left and right adjustable crown bands 210, 212 may increase asthe anterior crown band 214 and the left and right adjustable crownbands 210, 212 are decreasingly bent to conform to a larger crowncircumference.

HMD device 200 may further comprise left and right eye relief bands 250,252 that extend anteriorly from left and right sides of HMD device 200,wrapping around the anterior crown band 214, and passing through andoverlapping inside eye relief rack housing 230. Eye relief rack housing230 may comprise a notch 272 at a proximal center surface as well asopenings 264 at distal left and right surfaces. Openings 264 may bepositioned opposite from sliding structures 262 extending from anteriorcrown band 214. Openings 264 and notch 272 may aid in increasingflexibility of the eye relief rack housing 230, which may increaseconformity and fit of the anterior crown band 214 to a user's crown.Furthermore, openings 264 may allow sliding structures 262 to slidablyengage the left and right eye relief bands 250, 252. As shown in FIGS.6-9, Anterior crown band 214 may further include cutouts (similar tocutouts 114) for increasing a flexibility and reducing a weight ofanterior crown band 214.

Referring to FIGS. 7-9, a side view, a sectional view taken at section8-8 of FIG. 6, and an anterior cutaway view of HMD device 200,respectively, are illustrated. In particular, FIG. 9 illustrates ananterior view of HMD device 200 with the eye relief rack housing 270cutaway. Left and right eye relief bands 250, 252 may include left andright eye relief racks 280, 282, respectively. As shown via the cutawaysection 299, wherein the right eye relief rack 282 is partially cutawayto reveal the left eye relief rack 280, left and right eye relief racks280, 282 may overlap inside the eye relief rack housing 270. Left andright eye relief racks may be engaged to pinion 290 wherein rotationalmotion of pinion 290 actuates linear motion of the left and right eyerelief racks in opposite linear directions aligned with the anteriorcrown band 214. Pinion 290 may be positioned at a central anteriorlocation of the anterior crown band 214, and may be mounted to pinionbase 294 to maintain the central anterior location of the pinion 290even when it is rotating. Pinion base 294 may be mounted to eye reliefrack housing 270. As such, applying a pushing or pulling force to thedisplay toward or away from a user's crown when the HMD is worn on auser's crown may initiate sliding of the left and right eye relief racksand rotation of the pinion 290 in a timed manner such that an eye reliefdistance 3792 is decreased or increased, respectively. In particular,applying a pushing force to the display assembly 3790 may initiaterotation of pinion 290 in a first direction to slide left and right eyerelief racks 280, 282 wherein a length of the left and right eye reliefracks 280, 282 overlapping inside eye relief rack housing 270 may beincreased in the timed manner. Furthermore, applying a pulling force tothe display assembly 3790 may initiate rotation of pinion 290 in asecond direction to slide left and right eye relief racks 280, 282wherein a length of the left and right eye relief racks 280, 282overlapping inside eye relief rack housing 270 may be decreased in thetimed manner.

Left and right eye relief bands 250, 252 may further comprise attachmentstructures 140 mounted at posterior ends of the left and right eyerelief bands 250, 252. Attachment structures 140 may comprise aplurality of mounting holes to which armature 3750 may be mounted. Inother examples, attachment structures may comprise hooks, clips, rivets,screw, and other attachment mechanisms. The armature supports andaffixes a display assembly 3790 to the HMD device 100, the displayassembly 3790 mounted at left and right sides to respective distal ends3756 of the left and right arms 3752, 3754. In this way, uponapplication of a pushing force towards or a pulling force away from theuser's eyes to the display assembly 3790, an eye relief distance ofdisplay assembly 3790 may be adjusted in a timed manner relative to theleft and right sides. Furthermore, the adjusting the eye relief distancemay comprise of adjusting a length of the left and right eye reliefbands 250, 252 passing through and overlapping inside eye relief rackhousing 270, since the left and right eye relief bands 250, 252 aregrounded to the eye relief rack housing 270 and are not grounded to thecrown rack housing 230, left and right eye relief bands 250, 252 do haveto be adjusted to compensate for adjustments in crown circumference inorder to maintain an eye relief distance 3792.

Left and right eye relief bands 250, 252 may be held adjacent to adistal surface of the anterior crown band 214 by sliding structures 116and sliding structures 262. Thus, attachment structures 140 translate ina linear direction anteriorly and posteriorly adjacent to the distalsurface of the anterior crown band 214 as the eye relief distance 2792is increased and decreased, respectively. Furthermore, slidingstructures 116, sliding structures 262, and eye relief rack housing 270may aid in encouraging left and right eye relief bands 250, 252 to bendand conform to the shape of the anterior crown band 214 as crowncircumference is increased and decreased, and as eye relief distance isadjusted. Further still, the elasticity of the anterior crown band 214,left and right eye relief bands 250, 252, and the left and rightadjustable crown bands 210, 212 may cause the bent left and right eyerelief bands 250, 252 to continually press against the slidingstructures 116 and 262. In this way, a position (e.g. eye reliefdistance 3792) of the left and right eye relief bands 250, 252 may bemaintained by a friction force between the left and right eye reliefbands 250, 252 and the anterior crown band 214. Furthermore, frictionalforces between the engaged gears of the pinion 290 and left and righteye relief racks 280, 282 may aid in maintaining a position (e.g. eyerelief distance 3792) of the left and right eye relief bands 250, 252.Further still, frictional forces between the engaged gears of crown rackpinion 292 and left and right crown racks 216 may aid in maintaining aposition (e.g. crown circumference) of the left and right adjustablecrown bands 210, 212.

As shown in FIG. 9, HMD device 200 may further comprise a curved housingposterior support band 136 with cutouts 138, and a curved anterior crownsupport 236 with cutouts 238. Both anterior and posterior crown supports236, 136 may aid in providing a comfortable fit of HMD device 200 to auser's crown. Cutouts 238, 138 may aid in increasing a flexibility ofthe anterior and posterior crown supports 236, 136 and may aid inreducing a weight of the HMD device 200. Thus HMD device 200 maycomprise a crown band adjustment mechanism, including left and rightadjustable crown bands 210, 212 and crown racks 216 mounted at posteriorends thereof, crown rack housing 230, knob 220, and crown rack pinion292. Furthermore, HMD device 200 may comprise an eye relief distanceadjustment mechanism configured to move the left and right arms 3752,3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance fromthe display to an eye of the user when the crown band is fitted on thecrown of the user. Further still, in this way, eye relief distance maybe adjusted independently of crown circumference. In other words,adjusting crown circumference may be performed without any or withreduced compensating adjustment for eye relief distance and vice versa.

Turning now to FIGS. 10 and 12, rear perspective and plan views of athird example embodiment of an HMD device 300 are illustrated. Alsoshown in FIGS. 10 and 12 are axes 303 and 302 indicating anterior,posterior, left, right, dorsal, and ventral directions. An HMD mayinclude HMD device 300 to be worn by a user, the HMD device 300comprising an adjustable crown band 310. The circumference of theadjustable crown band 310 may be adjusted by a crown band circumferenceadjusting mechanism coupled to the adjustable crown band, the crown bandcircumference adjusting mechanism configured to adjust a circumferenceof the crown band to releasably secure the crown band to the crown ofthe user. In the example embodiment shown in FIGS. 10-13, the crown bandcircumference adjusting mechanism comprises the adjustable crown band310, outer knob 326, rack housing 330, and crown racks 318. By rotatingthe outer knob 326 in a first or second direction, crown racks 318 maybe driven to either increase or decrease the circumference of theadjustable crown band 310, respectively. In this way, the crown bandcircumference adjusting mechanism may facilitate user adjustment of theHMD and thereby reduce a risk of the HMD being too tight and causingdiscomfort, or too loose and moving relative to the user's head duringuse, and negatively impacting the user's experience.

The HMD device 300 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 10-13, the eye relief distance adjustment mechanism comprises leftand right eye relief bands 360, inner knob 322, rack housing 330, eyerelief racks 368, attachment structures 140, and sliding structures 116.By rotating inner knob 322 in a first or second direction, eye reliefracks 268 may be driven to move the attachment structures 140 (alongwith the armature 3750 and display assembly 3790) in a timed manneranteriorly or posteriorly, respectively, along the distal surface of theadjustable crown band 310 to increase or decrease an eye relief distance3792, respectively. In this way, the eye relief distance adjustmentmechanism may facilitate adjusting eye relief distance of the HMD toincrease a user's ability to properly perceive the augmented realityelements displayed on the display of the HMD, while achieving acomfortable fit to the user's head size via the crown band circumferenceadjustment mechanism.

HMD device 300 comprises a flexible adjustable crown band 310 that wrapsaround the posterior of a user's crown when HMD is worn on by a user,and may be adjusted to accommodate a wide range of head circumferencesvia a knob assembly 320 located at a posterior center of the HMD device300. Adjustable crown band 310 also extends anteriorly, wrapping aroundan anterior end of a user's crown when the HMD device 300 is worn. Leftand right anterior ends 311 of adjustable crown band may overlap at ananterior side of HMD device 300, and may be coupled via fasteners 312.In other examples, left and right anterior ends 311 of adjustable crownband may form a unitary and contiguous band at an anterior side of HMDdevice 300.

Adjustable crown band 310 may include sliding structures 316, extendingsubstantially across left and right sides of the adjustable crown band310. Sliding structures 316 may extend distally from dorsal and ventraledges of adjustable crown band 310, and sliding structures 316 mayinclude lips 317 which extend ventrally and distally from dorsal andventral edges of adjustable crown band 310. In the example embodiment ofFIG. 10, sliding structures 316 comprise rails along the edges ofadjustable crown band 310; however, sliding structures 316 may compriseloops, bands, clips or other structures that guide and facilitatesliding of the eye relief bands 360 adjacent to a distal surface of theadjustable crown band 310 in a substantially linear direction alignedwith the adjustable crown band 310.

Anterior ends of eye relief bands 360 wrap around a distal (e.g. outer)surface of the adjustable crown band 310 extending from an anterior sideand extending along left and right sides. As described above slidingstructures 316 retain eye relief bands 360 adjacent to a distal surfaceof adjustable crown band 310. Accordingly, eye relief bands 360 bend andconform to a curvature and general shape of the adjustable crown band310. Eye relief bands 360 further comprise one or more attachmentstructures 140 positioned near anterior ends of the eye relief bands360. The attachment structures may comprise holes, protrusions, clips,couplings, braces, and other structures to which left and right arms3752, 3754 of an armature 3750 may be attached. Accordingly, a displayassembly 3790 may be supported and affixed via the armature 3750 to theHMD device 100, the display assembly 3790 mounted at left and rightsides to respective distal ends 3756 of the left and right arms 3752,3754 of the armature 3750. HMD device 300 may further comprise holes 319on a proximal anterior side of adjustable crown band 310 and may aid inassembly and mounting of the armature 3750 via attachment structures140.

On posterior left and right sides of the HMD device 300, the eye reliefbands 360 may pass through openings 340 in the adjustable crown band310. Openings 340 may be located on left and right sides of theadjustable crown band 310, and the openings 340 may comprise a channel,slot, or other type of opening, shaped to guide the eye relief bands 360from a distal (outer) surface to a proximal (inner) surface of theadjustable crown band 310. The shape of opening 340 may aid in smoothlyguiding the eye relief bands 360 to reduce kinking or abrupt transitionsin the curvature of the eye relief bands 360, thereby maintainingcomfort-of-fit of the HMD device 300 when worn by a user. After passingthrough openings 340, the eye relief bands 360 may pass through andoverlap inside rack housing 330 mounted at a posterior end of HMD device300. In this way, eye relief bands 360 are positioned between aposterior crown of the user and the adjustable crown bands 310 when HMDdevice 300 is worn by the user. Passing the eye relief bands 360 throughto an interior (proximal) side of the adjustable crown bands 310 at aposterior side may aid outer knob 326 in more compactly adjusting thecrown bands. Furthermore, designating the outer knob for adjusting thecrown circumference aids in the user being able to easily access thecrown adjustment mechanism; the crown adjustment mechanism may be morefrequently adjusted as compared to the eye relief distance adjustmentmechanism.

Referring to FIGS. 11 and 13, a side view and a cross-sectional viewtaken at section 13-13 of FIG. 12 of HMD device 300 are illustrated.Adjustable crown bands 310 include crown racks 318 mounted at posteriorends of adjustable crown bands 310, and eye relief bands 360 include eyerelief racks 368 mounted at posterior ends of eye relief bands 360.Crown racks 318 may pass through and overlap inside rack housing 330,and eye relief racks 368 may pass through and overlap inside rackhousing 330. Inside rack housing 330, crown racks 318 may be engagedwith a crown rack pinion and ratchet 392 mounted to rack housing 330,while eye relief racks 368 may be engaged to an eye relief pinion andratchet 390 mounted to rack housing 330. Furthermore divider 398 mayseparate rack housing 330 into two compartments. Thus, the eye reliefracks 368 may pass through and overlap inside an inner compartment ofrack housing 330, while crown racks 318 may pass through and overlapinside an outer compartment of rack housing 330. In this way divider 398may reduce mechanical interference between the crown racks 318 and theeye relief racks 368 inside the housing and thereby aid in increasingsmooth operation of the HMD device 300.

HMD device 300 may comprise knob assembly 320. Knob assembly 320 maycomprise nested knobs, including outer knob 326 and inner knob 322.Outer knob 326 may be rotatably coupled to crown pinion and ratchet 392;when outer knob 326 is rotated in a first direction, crown pinion andratchet 392 may engage crown racks 318 and a length of crown racks 318overlapping in rack housing 330 may increase, thereby reducing acircumference of the HMD device 300. When outer knob is rotated in asecond direction, crown pinion and ratchet 392 may engage crown racks318 and a length of crown racks 318 overlapping in rack housing 330 maydecrease, thereby increasing a circumference of the HMD device 300.

Inner knob 322 may be rotatably coupled to eye relief pinion and ratchet390 via eye relief drive shaft 394; when inner knob 322 is rotated in afirst direction, eye relief pinion and ratchet 390 may engage eye reliefracks 368 and a length of eye relief racks 368 overlapping in rackhousing 330 may increase, thereby reducing an eye relief distance of theHMD device 300. When inner knob 322 is rotated in a second direction,eye relief pinion and ratchet 390 may engage eye relief racks 368 viaeye relief drive shaft 394, and a length of eye relief racks 368overlapping in rack housing 330 may decrease, thereby increasing an eyerelief distance of the HMD device 300. Eye relief distance may beadjusted via rotation of inner knob 322 because as the length of the eyerelief racks 368 overlapping in rack housing 330 increases or decreases,a position of the attachment structures 140 (to which armature 3750 withdisplay assembly 3790 is mounted) moves linearly aligned with theadjustable crown band 310 in an anterior direction or a posteriordirection, respectively, relative to the eyes of the user when the HMDdevice 300 is worn by the user.

The adjustment for eye relief distance may comprise the adjustmentlength for the crown circumference, since both the adjustable crownbands 310 and the eye relief bands 360 are grounded to the rack housing330. As such, when the circumference of the adjustable crown bands 310is adjusted via outer knob 326, the eye relief bands 360 may also beadjusted via inner knob 322 to maintain the same eye relief distance ofthe display assembly 3790 and the eyes of the user. Furthermore, becausethe eye relief racks 368 mounted on the left and right ends of eyerelief bands 360 are grounded to the eye relief pinion and ratchet 390,rotation of the eye relief pinion and ratchet 390 actuates translationof the eye relief bands 360 in a timed manner. As such, the eye reliefdistance 3792 of display assembly 3790 may be adjusted in the timedmanner with respect to the left and right sides of the HMD device 300.Further still, because the crown racks 318 mounted on the left and rightends of adjustable crown bands 310 are grounded to the crown adjustmentpinion and ratchet 392, rotation of the crown adjustment pinion andratchet 392 actuates translation of the adjustable crown bands 310 in atimed manner. As such, the crown circumference of HMD device 300 may beadjusted in the timed manner with respect to the left and right sides ofthe HMD device 300.

Crown pinion and ratchet 392 and eye relief pinion and ratchet 390 mayimpart a ratcheting capability to HMD device 300. In particular, theratcheting capability may cause the movement of the adjustable crownbands 310 and the eye relief bands 360 to be non-backdrivable. In otherwords, the eye relief distance and the crown circumference may not beadjusted without rotation of the inner knob 322 and the outer knob 326,respectively. In particular, the crown pinion and ratchet 392 and theeye relief pinion and ratchet 390 may not be rotated by only applying apushing or pulling force on the display assembly 3790. Furthermore, thecrown pinion and ratchet 392 and the eye relief pinion and ratchet 390may be locked by the ratcheting properties thereof, until rotation ofthe inner knob 322 and the outer knob 326, respectively, are initiated.The non-backdrivable nature of HMD device 300 may be advantageousbecause a particular eye relief distance and a particular crown fit(e.g., crown circumference) of the HMD device 300 may be maintainedbetween multiple doffs and dons of the HMD. As such a user may use theHMD, remove the HMD while performing other activities, and then returnto use the HMD again, without fear of the HMD fit or eye relief distancehaving changed. The non-backdrivable nature of HMD device 300 thusincreases a user-friendliness of the HMD, and may reduce a user setuptime associated with the HMD. Furthermore, the crown band circumferenceadjusting mechanism and the eye relief distance adjustment mechanism ofHMD device 300 may be advantageous because both eye relief distance andcrown circumference may be adjusted independently of one another at asingle (central posterior) position on the HMD device 300.

Turning now to FIGS. 14, 14A, 15, and 16, posterior perspective, partialanterior exploded perspective, left side, posterior views areillustrated of a fourth example embodiment of an HMD device 400.Furthermore, FIGS. 17, 18, and 18A illustrate partial cross-sectionalviews and a partial exploded perspective view of a fourth exampleembodiment of an HMD device 400. An HMD may include HMD device 400 to beworn by a user, the HMD device 400 comprising left and right adjustablecrown bands 410. The circumference of the left and right adjustablecrown bands 410 may be adjusted by a crown band circumference adjustingmechanism coupled to left and right adjustable crown bands 410, thecrown band circumference adjusting mechanism configured to adjust acircumference of the crown band to releasably secure the crown band tothe crown of the user. In the example embodiment shown in FIGS. 14, 14A,15-18, and 18A, the crown band circumference adjusting mechanismcomprises the left and right adjustable crown bands 410, shiftable knob422, housing 430, timing band 460, timing band crown racks 466, firstand second anterior crown racks, and first and second posterior crownracks 418. By shifting shiftable knob 422 to a first indexed position,and by rotating the shiftable knob 422 in a first or second direction,first and second posterior crown racks 466 may be driven by pinion 490and first and second anterior crown racks may be driven by timing band460 to either increase or decrease the circumference of the adjustablecrown band 410, respectively. In this way, the crown band circumferenceadjusting mechanism may facilitate user adjustment of the HMD andthereby reduce a risk of the HMD being too tight and causing discomfort,or too loose and moving relative to the user's head during use, andnegatively impacting the user's experience.

The HMD device 400 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 14, 14A, 15-18, and 18A, the eye relief distance adjustmentmechanism comprises left and right adjustable crown bands 410, timingband 460, shiftable knob 422, housing 430, timing band eye relief racks462 and 464, timing band crown racks 466, attachment structures 140, andsliding structures 116. By shifting shiftable knob 422 to a secondindexed position, and by rotating the shiftable knob 422 in a first orsecond direction, timing band eye relief racks 462 and 464 and timingband crown racks 466 may be driven by timing band 460 to move theattachment structures 140 (along with the armature 3750 and displayassembly 3790) in a timed manner anteriorly or posteriorly,respectively, along the distal surface of the adjustable crown band 410to increase or decrease an eye relief distance 3792, respectively. Inthis way, the eye relief distance adjustment mechanism may facilitateadjusting eye relief distance of the HMD to increase a user's ability toproperly perceive the augmented reality elements displayed on thedisplay of the HMD, while achieving a comfortable fit to the user's headsize via the crown band circumference adjustment mechanism.

FIGS. 14 and 14A includes axes 403 and 405 respectively, showinganterior, posterior, dorsal, ventral, left, and right directions. HMDdevice 400 comprises left and right flexible crown bands 410 that wraparound the left and right side, respectively, of a user's crown when HMDdevice 400 is worn by the user. Each of left and right crown bands 410may each comprise first and second anterior racks 412, 413 mounted at ananterior end and first and second posterior racks (not shown) mounted ata posterior end. HMD device 400 may further comprise a timing band 460that wraps around a left side of the HMD device. Timing band 460includes an anterior timing band eye relief adjustment rack 462 mountedat an anterior end of the timing band 460, and a posterior timing bandcrown rack 466 and a posterior timing band eye relief rack 464 mountedat a posterior end of the timing band 460. The anterior timing band eyerelief adjustment rack 462, posterior timing band eye relief adjustmentracks 464, and posterior timing band crown adjustment racks 466 may beshifted in an anterior-posterior axis relative to the anterior andposterior timing band eye relief adjustment racks in the HMD device 400.Furthermore, the anterior and posterior timing band crown adjustmentracks and the anterior and posterior timing band eye relief adjustmentracks may be positioned on opposite (e.g., dorsal and ventral, orventral and dorsal) sides relative to the posterior pinion 490. In thisway, when posterior pinion 490 is rotated in a first direction whileengaging anterior and posterior timing band crown adjustment racks thetiming band may be driven in an opposite direction from when posteriorpinion 490 is rotated in the first direction while engaging the anteriorand posterior timing band eye relief adjustment racks.

The first and second anterior racks e.g., 412, 413 of FIG. 14A of theleft and right crown bands 410, and the anterior timing band eye reliefadjustment rack 462 may be engaged to an anterior pinion 478 mounted atand rotatably coupled to anterior housing 470 via anterior pinion axle477. Anterior housing 470 may include an anterior housing rear cover 474and an anterior housing front cover 476. As shown in FIG. 14A, the leftand right crown bands 410 and the timing band 460 may pass through leftand right openings in the anterior housing rear cover 474. Anteriorhousing front cover 476 may be removably affixed to an anterior side ofthe anterior housing rear cover 474, thereby retaining anterior pinion478, first and second anterior racks 412, 413 of the left and rightcrown bands, and eye relief adjustment racks engaged within anteriorhousing 470. The first and second posterior crown racks 418 of left andright crown bands, the posterior timing band crown racks 466, and theposterior timing band eye relief racks 464 may be engaged to a posteriorpinion 490 mounted at and rotatably coupled to posterior housing 430. Inthis way: first anterior rack of the left crown band and first anteriorrack of the right crown band may pass through and overlap insideanterior housing 470; second anterior rack of the left crown band andsecond anterior rack of the right crown band may pass through andoverlap inside anterior housing 470; first posterior rack of the leftcrown band and first posterior rack of the right crown band may passthrough and overlap inside posterior housing 430; and second posteriorrack of the left crown band and second posterior rack of the right crownband may pass through and overlap inside posterior housing 430.

A shiftable knob assembly 420 may be mounted to posterior housing 430 ata central posterior position of HMD device 400. FIG. 18 illustrates across-sectional view of HMD device 400 taken at section 18-18 of FIG.14. Shiftable knob assembly 420 may comprise a shiftable knob 422, whichmay be rotatably coupled to posterior pinion 490. As such, uponrotation, the shiftable knob assembly 420 may drive posterior pinion490. Posterior pinion 490 may comprise posterior and anterior grooves494, 495 encircling a circumference of posterior pinion 490 at adjacentaxial positions. Furthermore, shiftable knob assembly 420 may alsotranslate or shift in the anterior-posterior axis to occupy one of atleast two indexed positions corresponding to the posterior and anteriorgrooves 494, 495. The positioning of shiftable knob assembly 420 may beindexed via a ball detent 496 residing in a ball detent chamber 498adjacent to the posterior pinion 490. A diameter and shape of the balldetent may correspond to a diameter and shape of the posterior andanterior grooves 494, 495, such that when the posterior pinion isshifted to one of the at least two indexed positions, ball detent 496 isseated in one of the posterior and anterior grooves 494, 495 andpartially protrudes from ball detent chamber 498.

Ball detent 496 may be urged to partially protrude from ball detentchamber 498 in a dorsal direction by a spring or other elastic membercontained within ball detent chamber 498. When the shiftable knobassembly 420 is shifted between the posterior or anterior axial indexedposition, the protruding ball detent 496 is first pushed into the balldetent chamber 498, the spring or elastic material therein beingcompressed by the ungrooved portion of the posterior pinion betweenposterior and anterior grooves 494, 495, which allows the posteriorpinion 490 to be shifted. When the posterior pinion 490 has shifted sothat one of the posterior and anterior grooves 494, 495 is aligned orpartially aligned with the ball detent chamber 498, ball detent 496seats in the aligned groove, and the posterior pinion 490 shifts to thecorresponding indexed position.

When posterior pinion 490 is shifted to a first indexed position, (e.g.ball detent 496 is positioned in anterior groove 495, as shown in FIG.18), the HMD device 400 may be configured to adjust a crowncircumference. When adjusting crown circumference, ball detent 496 maybe seated in the anterior groove 495, and posterior pinion 490 may bepositioned to drive a stationary pinion 480. Furthermore, stationarypinion 480 may be engaged to drive first and second posterior crownracks 418 of the left and right crown bands when shiftable knob 422 isrotated. Further still, when posterior pinion 490 is shifted to a firstindexed position, posterior pinion 490 may engage the posterior timingband crown rack 466.

Thus, in one example embodiment, rotating shiftable knob 422 may driverotation of the posterior pinion 490, which in turn drives translationof the timing band 460 via timing band crown racks 466. The translationof the timing band 460 via crown racks 466 may drive rotation of theanterior pinion 478 mounted to the anterior housing 470 such that thefirst and second anterior racks of left and right crown bands areadjusted to increase or decrease a circumference of HMD device 400. Inparticular, the first and second anterior racks of the left and rightcrown bands and the first and second posterior crown racks 418 of theleft and right crown bands may be adjusted in a timed manner via timingband 460 to increase or decrease a circumference of HMD device 400,while maintaining an eye relief distance 3792. Specifically, lengths offirst and second anterior racks of the left and right crown bandspassing through and overlapping inside the anterior housing 470 mayincrease in a timed manner via timing band 460 while lengths of firstand second posterior crown racks 418 of the left and right crown bandspassing through and overlapping inside the posterior housing 430increase in the timed manner via timing band 460. Furthermore, lengthsof first and second anterior racks of the left and right crown bandspassing through and overlapping inside the anterior housing 470 maydecrease in a timed manner via timing band 460 while lengths of firstand second posterior crown racks 418 of the left and right crown bandspassing through and overlapping inside the posterior housing 430decrease in the timed manner via timing band 460. Because the first andsecond posterior crown racks 418 of the left and right crown bands areadjusted in a corresponding timed manner with the adjustment of thefirst and second anterior racks of the left and right crown bands, eyerelief distance is maintained approximately constant while the crowncircumference is adjusted. Accordingly, when a shiftable knob 422 isshifted to the first indexed position and rotated in either a first orsecond direction, a circumference of the HMD device 400 may be adjusted(e.g., increased or decreased) to fit a user's crown, while maintainingan eye relief distance.

In another example embodiment, adjustment of the crown circumference maybe performed by disengaging the posterior timing band eye reliefadjustment racks 464 when posterior pinion 490 is shifted to a firstindexed position. Thus, when posterior pinion is 490 rotated, timingband 460 and anterior timing band eye relief adjustment rack 462 remainstatic in relation to 116. Furthermore, anterior pinion 478, and thefirst and second anterior racks of left and right crown bands alsoremain stationary. Thus, adjustment of the crown circumference may beperformed via adjustment of the first and second posterior crown racks418 (and not via adjustment of the first and second anterior racks 412,413 of the left and right crown bands 410) by rotating shiftable knob422, and thereby driving rotation of the posterior pinion 490.

When posterior pinion 490 is shifted (e.g. anteriorly relative to thefirst indexed position) to a second indexed position, the HMD device 400may be configured to adjust an eye relief distance. When adjusting eyerelief distance, ball detent 496 may be seated in the posterior groove494, and posterior pinion 490 may be positioned to drive timing band eyerelief rack 464. Furthermore, posterior pinion may remain rotationallycoupled to stationary pinion 480 via a keyed clutch 492 (see FIGS. 18,18A). Further still, when posterior pinion 490 is shifted to the secondindexed position, posterior pinion 490 may engage the posterior timingband eye relief rack 464. Thus, rotating shiftable knob 422 may driverotation of the posterior pinion 490, which in turn drives translationof the timing band 460 via timing band eye relief racks 464. Thetranslation of the timing band 460 (e.g., timing band 460 slidesrelative to sliding structures 116) via eye relief racks 464 may driverotation of the anterior pinion 478 mounted to the anterior housing 470via anterior timing band eye relief adjustment rack 462 such that thefirst and second anterior racks of left and right crown bands areadjusted to increase or decrease an eye relief distance of HMD device400. In particular, the first and second anterior racks of the left andright crown bands and the first and second posterior crown racks 418 ofthe left and right crown bands may be adjusted in a timed manner viatiming band 460 to increase or decrease an eye relief distance 3792 ofHMD device 400, while maintaining a crown circumference. Specifically,lengths of first and second anterior racks of the left and right crownbands passing through and overlapping inside the anterior housing 470may decrease in a timed manner via timing band 460 while lengths offirst and second posterior crown racks 418 of the left and right crownbands passing through and overlapping inside the posterior housing 430may increase in the timed manner via timing band 460. Furthermore,lengths of first and second anterior racks of the left and right crownbands passing through and overlapping inside the anterior housing 470may increase in a timed manner via timing band 460 while lengths offirst and second posterior crown racks 418 of the left and right crownbands passing through and overlapping inside the posterior housing 430may decrease in the timed manner via timing band 460. Accordingly, whena shiftable knob 422 is shifted to the second indexed position androtated in either a first or second direction, an eye relief distance ofthe HMD device 400 may be adjusted (e.g., increased or decreased), whilemaintaining a circumference of the HMD device 400 to maintain fit to auser's crown.

When posterior pinion 490 is shifted (e.g. anteriorly relative to thefirst indexed position) to a second indexed position, and the HMD device400 may be configured to adjust an eye relief distance, a position ofattachment structures 140 may be translated in an anterior or posteriordirection to increase or decrease eye relief distance, respectively.When posterior pinion 490 is shifted (e.g. posteriorly, as shown in FIG.18) to the first indexed position, and the HMD device 400 may beconfigured to adjust a circumference, a position of the attachmentstructures 140 in an anterior-posterior axis remains constant.Accordingly, depending on whether posterior pinion 490 is shifted to thefirst or second indexed position, the posterior pinion 490 engages witheither the timing band crown adjustment racks or the timing band timingband eye relief adjustment racks respectively, to change a drivedirection of the timing band relative to a rotation direction of theshiftable knob 422.

Posterior pinion 490 and stationary 480 may impart a ratchetingcapability to HMD device 400. In particular, the ratcheting capabilitymay cause the movement of the left and right adjustable crown bands 410and the timing band 460 to be non-backdrivable. In other words, the eyerelief distance and the crown circumference may not be adjusted withoutrotation of the shiftable knob 422. In particular, the posterior pinion490 and the anterior pinion 478 may not be rotated by only applying apushing or pulling force on the display assembly 3790. Furthermore, theposterior pinion 490 and the anterior pinion 478 may be locked by theratcheting properties thereof, until rotation of the shiftable knob 422is initiated. The non-backdrivable nature of HMD device 400 may beadvantageous because a particular eye relief distance and a particularcrown fit (e.g., crown circumference) of the HMD device 400 may bemaintained between multiple doffs and dons of the HMD. As such a usermay use the HMD, remove the HMD while performing other activities, andthen return to use the HMD again, without fear of the HMD fit or eyerelief distance having changed. The non-backdrivable nature of HMDdevice 400 thus increases a user-friendliness of the HMD, and may reducea user setup time associated with the HMD. Furthermore, the crown bandcircumference adjusting mechanism and the eye relief distance adjustmentmechanism of HMD device 400 may be advantageous because both eye reliefdistance and crown circumference may be adjusted at a single (centralposterior) position on the HMD device 300, using a single knob assembly.Further still HMD device 400 reduces the total number of bands which mayreduce the complexity of operation, and reduce a weight of HMD device400.

Turning now to FIGS. 19, 20, and 23, posterior perspective, plan, andside views respectively of a fifth embodiment of an HMD device 500 areillustrated. An HMD may include HMD device 500 to be worn by a user, theHMD device 500 comprising a flexible adjustable crown band 510. Thecircumference of the adjustable crown band 510 may be adjusted by acrown band circumference adjusting mechanism coupled to the adjustablecrown band 510, the crown band circumference adjusting mechanismconfigured to adjust a circumference of the crown band to releasablysecure the crown band to the crown of the user. In the exampleembodiment shown in FIGS. 19-23, the crown band circumference adjustingmechanism comprises the adjustable crown band 510, knob 520, housing530, timing bands 560, and crown racks 518. By rotating the knob 520 ina first or second direction, the crown racks 418 may be driven to eitherincrease or decrease the circumference of the adjustable crown band 510,respectively. In this way, the crown band circumference adjustingmechanism may facilitate user adjustment of the HMD and thereby reduce arisk of the HMD being too tight and causing discomfort, or too loose andmoving relative to the user's head during use, and negatively impactingthe user's experience.

The HMD device 500 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 19-23, the eye relief distance adjustment mechanism compriseadjustable crown band 510, timing bands 560, knob 520, housing 530,timing band racks 568, attachment structures 540, and sliding structures116. By rotating the knob 520 in a first or second direction, timingband racks 568 may be driven to move the attachment structures 540(along with the armature 3750 and display assembly 3790) in a timedmanner anteriorly or posteriorly, respectively, along the distal surfaceof the adjustable crown band 510 to increase or decrease an eye reliefdistance 3792, respectively. In this way, the eye relief distanceadjustment mechanism may facilitate adjusting eye relief distance of theHMD to increase a user's ability to properly perceive the augmentedreality elements displayed on the display of the HMD, while achieving acomfortable fit to the user's head size via the crown band circumferenceadjustment mechanism.

As illustrated in FIGS. 19, 20, and 23, axes 501, 502, and 503illustrate anterior, posterior, dorsal, ventral, left, and rightdirections. When HMD device 500 is worn by a user, flexible adjustablecrown band 510 wraps around the user's crown at an angle 545 raised fromthe anterior-posterior axis. In one example angle 545 may be less than35°, but greater than 10°. In particular, angle 545 may be approximately30°. If angle 545 is greater than 35°, achieving a comfortable crown fitof HMD device 500 may be reduced. In this way, the HMD may be wornhigher on a user's head, while maintaining an adjustment of the eyerelief distance substantially in an anterior-posterior direction. At theposterior side of HMD device 500, ends of adjustable crown band 510 passthrough and overlap inside housing 530. Adjustable crown band 510 maycomprise crown racks 518 mounted to the ends of the adjustable crownband 510. Thus, the crown racks 518 may pass through and overlap insidehousing 530, and may be engaged to a pinion 590 mounted at housing 530.Pinion 590 may be rotatably coupled to knob 520 such that when knob 520is rotated in a first or second direction, lengths of the crown racks518 passing through and overlapping inside housing 530 increase ordecrease, respectively, thereby decreasing or increasing a crowncircumference, respectively.

Timing bands 560 may wrap around a distal (outer) surface of adjustablecrown band 510. Posterior ends of timing bands 560 may comprise timingband racks 568 passing through and overlapping inside housing 530.Housing 530 may comprise an inner housing 532 and an outer housing 534to separate the crown racks 518 and the timing band racks 568 inside thehousing. Accordingly, crown racks 518 may pass through and overlapinside inner housing 532, and timing band racks 568 may pass through andoverlap inside outer housing 534. Furthermore, timing band racks 568 maybe engaged to a second posterior pinion (not shown) coaxial with pinion590. Timing band racks 568 may be timed corresponding to secondposterior pinion via a friction controlled mechanism. Thus, when knob520 is rotated in a first or second direction, second posterior pinionmay be rotated in a first or second direction, and lengths of the timingband racks 568 passing through and overlapping inside housing 530 mayincrease or decrease, respectively.

Anterior ends of the timing bands 560 include side racks 566 at left andright sides of the HMD device 500. Side racks 566 may be engaged toattachment structures 540 positioned at left and right sides of HMDdevice 500. Turning now to FIGS. 21-22, partial side views of HMD device500 are illustrated. In particular, FIG. 22 shows the partial side viewof HMD device 500 of FIG. 21 with eye relief rack holder 548 removed toclearly show an exposed side view of the eye relief rack 547. As shownin FIGS. 21-22, attachment structures 540 may comprise side pinions 549,eye relief racks 547, eye relief rack holders 548, and fasteners 542.Accordingly side racks 566 may be engaged to side pinions 549 ofattachment structures 540. Furthermore, rotating knob 520 in a first orsecond direction may drive side racks 566 to translate posteriorly oranteriorly (at an angle 545) in a timed manner (e.g., synchronized totranslate in the same direction at the same time, and at the same rate)along the crown band 510 respectively, which in turn may drive sidepinions to rotate in a timed manner such that eye relief racks 547translate posteriorly or anteriorly in the timed manner, respectively.As described previously, sliding structures 116 may retain timing bands560 adjacent to the distal (outer) surface of adjustable crown band 510and may maintain translation of timing bands 560 in a substantiallylinear direction aligned with adjustable crown band 510. Further still,left and right arms 3752, 3754 of armature 3750 may be mounted toattachment structures 540 at eye relief racks 547. In this way, rotatingknob 520 may adjust (e.g., decrease or increase) an eye relief distance3792 between the users eyes 3794 and the display assembly 3790 in thetimed manner relative to the left and right sides. Furthermore, becauseeye relief rack holders 548 are angled from adjustable crown band 510 atangle 545, eye relief racks 547 slide and translate at an angle 545 tothe adjustable crown band 510, and adjustment eye relief distance maythus be maintained in a direction substantially aligned with theanterior-posterior axis even though the adjustable crown band 510 andthe crown circumference adjustment are aligned with an axis at angle 545to the anterior-posterior axis. Fasteners 542 may be configured toadjustably fix eye relief rack holders 548 to be positioned at angle 545to the adjustable crown band. In some examples, fasteners 542 may beadjusted to adjust (increase and/or decrease) angle 545.

In another example, adjusting the eye relief distance may furthercomprise applying a pushing force to the display towards the user's eyesor applying a pulling force to the display away from the user's eyes toovercome friction between the side pinions 549, side racks 566, eyerelief racks 547, and eye relief rack holders 548. Furthermore, applyingthe pushing or pulling force to the display may driving timing bandracks 568 via the friction-engaged second posterior pinion, but may notdrive pinion 590. In this manner, eye relief distance may be adjustedindependently from crown circumference. In a further example, a nestedknob (analogous to nested knob assembly 320) may be provided in place ofknob 520 for adjusting the crown circumference independently fromadjusting the timing bands 560 for setting the eye relief distance.

Turning now to FIGS. 24, 27, and 28, posterior perspective, plan, andside views respectively of a sixth embodiment of an HMD device 600 areillustrated. An HMD may include HMD device 600 to be worn by a user, theHMD device 600 comprising a flexible adjustable crown band 610. Thecircumference of the adjustable crown band 610 may be adjusted by acrown band circumference adjusting mechanism coupled to the adjustablecrown band 610, the crown band circumference adjusting mechanismconfigured to adjust a circumference of the crown band to releasablysecure the crown band to the crown of the user. In the exampleembodiment shown in FIGS. 24-28, the crown band circumference adjustingmechanism comprises the adjustable crown band 610, knob 620, housing630, and crown racks 618. By rotating the knob 620 in a first or seconddirection, the crown racks 618 may be driven to either increase ordecrease the circumference of the adjustable crown band 610,respectively. In this way, the crown band circumference adjustingmechanism may facilitate user adjustment of the HMD and thereby reduce arisk of the HMD being too tight and causing discomfort, or too loose andmoving relative to the user's head during use, and negatively impactingthe user's experience.

The HMD device 600 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 24-28, the eye relief distance adjustment mechanism compriseadjustable crown band 610, timing band 660, knob 620, housing 630, sideracks 668, attachment structures 640, and sliding structures 116. Byrotating the knob 620 in a first or second direction, side racks 668 maybe driven to move the attachment structures 640 (along with the armature3750 and display assembly 3790) in a timed manner anteriorly orposteriorly, respectively, along the distal surface of the adjustablecrown band 610 to increase or decrease an eye relief distance 3792,respectively. In this way, the eye relief distance adjustment mechanismmay facilitate adjusting eye relief distance of the HMD to increase auser's ability to properly perceive the augmented reality elementsdisplayed on the display of the HMD, while achieving a comfortable fitto the user's head size via the crown band circumference adjustmentmechanism.

As illustrated in FIGS. 24, 27, and 28, axes 601, 602, and 603illustrate anterior, posterior, dorsal, ventral, left, and rightdirections. When HMD device 600 is worn by a user, flexible adjustablecrown band 610 wraps around the user's crown at an angle 645 raised fromthe anterior-posterior axis. In one example angle 645 may be less than35°, but greater than 10°. In particular, angle 645 may compriseapproximately 30°. If angle 645 is greater than 35°, achieving acomfortable crown fit of HMD device 600 may be reduced. In this way, theHMD may be worn higher on a user's head, while maintaining an adjustmentof the eye relief distance substantially in an anterior-posteriordirection. At the posterior side of HMD device 600, ends of adjustablecrown band 610 pass through and overlap inside housing 630. Adjustablecrown band 610 may comprise crown racks 618 mounted to the ends of theadjustable crown band 610. Thus, the crown racks 618 may pass throughand overlap inside housing 630, and may be engaged to a pinion 690mounted at housing 630. Pinion 690 may be rotatably coupled to knob 620such that when knob 620 is rotated in a first or second direction,lengths of the crown racks 618 passing through and overlapping insidehousing 630 increase or decrease, respectively, thereby decreasing orincreasing a crown circumference, respectively.

Timing band 660 may wrap around a distal (outer) surface of the anteriorside of adjustable crown band 610. Anterior ends of the timing band 660include side racks 668 at left and right sides of the HMD device 500.Side racks 668 may be engaged to attachment structures 640 positioned atleft and right sides of HMD device 600. Turning now to FIGS. 25-26,partial side views of HMD device 600 are illustrated. In particular,FIG. 26 shows the partial side view of HMD device 600 of FIG. 25 witheye relief rack holder 648 removed to clearly show an exposed side viewof the eye relief rack 647. As shown in FIGS. 25-26, attachmentstructures 640 may comprise side pinions 649, eye relief racks 547, eyerelief rack holders 648, and fasteners 642. Accordingly side racks 668may be engaged to side pinions 649 of attachment structures 640.Furthermore, applying a pushing force to display assembly 3790 towardsthe user's eyes or applying a pulling force to display assembly 3790away from the user's eyes may drive side racks 668 to translateposteriorly or anteriorly (at an angle 645) along the crown band 610respectively in a timed manner (e.g., in the same direction at the sametime), which in turn may drive side pinions to rotate in a timed mannersuch that eye relief racks 647 translate posteriorly or anteriorly inthe timed manner, respectively. Furthermore, side pinions may rotate ina first direction in a timed manner when eye relief racks 647 aretranslated posteriorly, and side pinions may rotate in a seconddirection in a timed manner when eye relief racks 647 are translatedanteriorly. As described previously, sliding structures 116 may retaintiming band 660 adjacent to the distal (outer) surface of adjustablecrown band 610 and may maintain translation of timing band 660 in asubstantially linear direction aligned with adjustable crown band 610.Further still, left and right arms 3752, 3754 of armature 3750 may bemounted to attachment structures 640 at eye relief racks 647. In thisway, rotating knob 620 may adjust (e.g., decrease or increase) an eyerelief distance 3792 between the users eyes 3794 and the displayassembly 3790 in the timed manner relative to the left and right sides.Furthermore, because eye relief rack holders 648 are angled fromadjustable crown band 610 at angle 645, eye relief racks 647 slide andtranslate at an angle 645 to the adjustable crown band 610, andadjustment eye relief distance may thus be maintained in a directionsubstantially aligned with the anterior-posterior axis even though theadjustable crown band 610 and the crown circumference adjustment arealigned with an axis at angle 645 to the anterior-posterior axis.Fasteners 642 may be configured to adjustably fix eye relief rackholders 648 to be positioned at angle 645 to the adjustable crown band.In some examples, fasteners 642 may be adjusted to adjust (increaseand/or decrease) angle 645.

In a further example, a nested knob (analogous to nested knob assembly320) may be provided in place of knob 620 for adjusting the crowncircumference independently from adjusting the timing bands 560 forsetting the eye relief distance. In another example, timing band 660 maybe routed distally over a user's crown from the left side to the rightside between attachment structures 640, instead of wrapping around ananterior side of the adjustable crown band 610.

Turning now to FIGS. 29 and 31, posterior perspective and anteriorperspective views respectively of a seventh embodiment of an HMD device700 are illustrated. An HMD may include HMD device 700 to be worn by auser, the HMD device 700 comprising a flexible adjustable crown band710. The circumference of the adjustable crown band 710 may be adjustedby a crown band circumference adjusting mechanism coupled to theadjustable crown band 710, the crown band circumference adjustingmechanism configured to adjust a circumference of the crown band toreleasably secure the crown band to the crown of the user. In theexample embodiment shown in FIGS. 29-33, the crown band circumferenceadjusting mechanism comprises the adjustable crown band 710, knobassembly 720, housing 730, and crown racks 718. By rotating the outerknob 726 of knob assembly 720 in a first or second direction, the crownracks 718 may be driven to either increase or decrease the circumferenceof the adjustable crown band 710, respectively. In this way, the crownband circumference adjusting mechanism may facilitate user adjustment ofthe HMD and thereby reduce a risk of the HMD being too tight and causingdiscomfort, or too loose and moving relative to the user's head duringuse, and negatively impacting the user's experience.

The HMD device 700 of the HMD may further comprise an eye reliefdistance adjustment mechanism configured to move the left and right arms3752, 3754 in a timed manner toward and away from the crown band along asubstantially linear path, to thereby adjust an eye relief distance 3792from the display assembly 3790 to an eye 3794 of a user when the crownband is fitted on the crown of the user. In the example embodiment ofFIGS. 29-33, the eye relief distance adjustment mechanism compriseadjustable crown band 710, flexible eye relief bands 760, knob assembly720, housing 730, eye relief racks 768, attachment structures 740, andsliding structures 116. By rotating the inner knob 722 of knob assembly720 in a first or second direction, eye relief racks 768 may be drivento move the attachment structures 740 (along with the armature 3750 anddisplay assembly 3790) in a timed manner anteriorly or posteriorly,respectively, along the distal surface of the adjustable crown band 710to increase or decrease an eye relief distance 3792, respectively. Inthis way, the eye relief distance adjustment mechanism may facilitateadjusting eye relief distance of the HMD to increase a user's ability toproperly perceive the augmented reality elements displayed on thedisplay of the HMD, while achieving a comfortable fit to the user's headsize via the crown band circumference adjustment mechanism.

As illustrated in FIGS. 29-31, axes 701, 702, and 703 illustrateanterior, posterior, dorsal, ventral, left, and right directions. Aflexible adjustable crown band 710 wraps around a user's crown when theHMD device 700 is worn. Ends of the adjustable crown band 710 maycomprise crown racks 718 overlapping inside and passing through ahousing 730 at a posterior side of HMD device 700. Crown racks 718 maybe engaged to a crown rack pinion 790 mounted to housing 730 androtatably coupled to outer knob 726 of knob assembly 720. Rotating outerknob 726 in a first direction or second direction may drive crown drive794, which in turn drives crown rack pinion 790 thereby increasing ordecreasing a length of crown racks 718 overlapping inside and passingthrough housing 730, and thereby decreasing or increasing a crowncircumference. The crown racks move in a timed manner, moving at thesame time, at the same rate, and in the same direction (towards or awayfrom crown rack pinion 790) because both crown racks 718 are engaged tocrown rack pinion 790.

Flexible eye relief bands 760 wrap around a posterior of the HMD device700 adjacent to a distal (outer) surface of adjustable crown band 710.Posterior ends of the eye relief bands 760 pass through and overlapinside housing where they are engaged to an eye relief rack pinion 792.Eye relief rack pinion 792 may be rotatably coupled to inner knob 722and may be coaxial with crown rack pinion 790. Housing 730 may comprisean inner housing 732 and an outer housing 734 separated by spacer 798.Crown racks 718 overlap inside and pass through inner housing 732, andeye relief racks 768 overlap inside and pass through outer housing 734.Accordingly, interference between the crown racks 718 and the eye reliefracks 768 inside housing 730 is reduced, and operation of HMD device 700is enhanced. Rotating inner knob 722 in a first or second directiondrives eye relief rack pinion 792 and may increase or decrease a lengthof the eye relief racks 768 passing through and overlapping inside outerhousing 734. The eye relief racks 768 move, translating in a timedmanner, moving at the same time, at the same rate, and in the samedirection (towards or away from eye relief rack pinion 792) because botheye relief racks 768 are engaged to eye relief rack pinion 792.

Posterior portions 763 of eye relief bands 760 may be substantiallylinear, and may comprise eye relief rack 768. An anterior portion 761 ofeye relief bands 760 may be two-dimensionally flexible, capable ofbending or flexing in distal-ventral direction and in the left-rightdirection. Anterior portion 761 may comprise a fishbone-like structure,including a flexible spine 764 and plate-like arms 762 extendingperpendicularly from distal and ventral sides of the spine 764. Arms 762may increase in dimension with increasing distance from flexible spine764 to impart increased flexibility to anterior portion 761. Rotatinginner knob 722 moves posterior ends of the eye relief bands 760,including the eye relief racks 768 in a substantially linear manner,aligned with the adjustable crown band 710. Furthermore, housing guides738 extending from left and right sides of housing 730 may guideposterior portions 763 the eye relief bands 760 as they are driven uponrotation of inner knob 722.

Anterior portion 761 of the eye relief bands 760 may be bent ventrallyfrom alignment with adjustable crown band 710 at angle 745 to besubstantially aligned with a posterior-anterior axis. In this way,anterior portions 761 may be guided along beams 716 extending anteriorlyfrom crown band 710 on the left and right sides, and angled ventrallyfrom alignment with adjustable crown band 710 at angle 745 to besubstantially aligned with a posterior-anterior axis. Beams 716 may alsobend in a left-right axis and are thus enables HMD device 700 to becapable of fitting a range of user crown widths. Beams 716 may comprisesliding structures 116 which may serve to retain anterior portions 761such that eye relief bands 760 slide adjacent to a distal (outer)surface of the beams 716 when eye relief distance of the HMD device 700is adjusted. As shown in FIGS. 32-33, anterior ends of eye relief bands760 may comprise attachment structures 740. Attachment structures 740may comprise fixtures 744 and opening 746 for mounting proximal ends ofleft and right arms 3752, 3754 of armature 3750 to which displayassembly 3790 is mounted. As described above with reference toattachment structures 740, attachment structures 740 may compriserivets, screws, bolts, hooks, openings, and other structures suitablefor mechanical coupling. In this way, rotation of inner knob 722 in afirst or second direction may adjust an eye relief distance betweendisplay assembly 3790 and the eyes 3794 of the user in a substantiallylinear manner aligned with an anterior-posterior axis. Furthermore,because left and right eye relief bands 760 are engaged to eye reliefrack pinion 792, movement of the left and right arms 3752, 3754 may bein a timed manner, wherein the left and right arms 3752, 3754 move atthe same time, in the same direction, and at the same rate.

As both the crown racks 718 and the eye relief racks 768 are grounded atthe posterior of HMD device 700 via crown rack pinion 790 and eye reliefrack pinion 792, respectively, adjustment of the eye relief distance maycomprise accounting for changes to the eye relief distance resultingfrom adjustments to crown circumference.

As described above with reference to knob assembly 320, knob assembly720 may be a non-backdrivable mechanism. As such, adjustment of thecrown circumference and the eye relief distance may not be performedwithout rotation of the outer knob 726 and the inner knob 722,respectively. The non-backdrivable nature of HMD device 700 may beadvantageous because a particular eye relief distance and a particularcrown fit (e.g., crown circumference) of the HMD device 700 may bemaintained between multiple doffs and dons of the HMD. As such a usermay use the HMD, remove the HMD while performing other activities, andthen return to use the HMD again, without fear of the HMD fit or eyerelief distance having changed. The non-backdrivable nature of HMDdevice 700 thus increases a user-friendliness of the HMD, and may reducea user setup time associated with the HMD.

In another embodiment of HMD device 700, eye relief distance may beadjusted by applying a pushing force to the display assembly 3790towards the user's eyes, or by applying a pulling force to the displayassembly 3790 away from the user's eyes to overcome friction, asdescribed analogously for HMD devices 200 and 300. In such anembodiment, HMD device 700 may comprise a single knob (similar to HMDdevices 200, 300), rather than a nested knob assembly 720.

Turning now to FIGS. 34-36, plan, perspective side, and side views areillustrated of an example of HMD device 500 comprising another type ofattachment structure 840 in place of attachment structure 540.Attachment structure 840 is shown integrated with HMD device 500 at leftand right sides in place of attachment structure 540, however,attachment structure 840 may also be integrated with other embodiments.Attachment structure 840 may comprise a flexible base 848 mounted viafastener 849 (e.g. screw, bolt, rivet, and the like) to eye relief rackholder 548. Fastener 849 may also be coupled to an end of side pinion549. At an anterior end of the flexible base 848, a mounting protrusion845 may be provided. The mounting protrusion 845 may comprise aparticular geometry to enable mechanical coupling or mating with acomplimentary socket of left and arms 3752, 3745 of armature 3750.Mounting protrusion 845 may comprise a flexible material such as asilicone rubber or polymer elastomer which can elastically deform whencompressed. Mounting protrusion may also comprise one or more sockets844, 846 corresponding to one or more protrusions in proximal ends ofleft and right arms 3750, 3752 for aiding in alignment of the attachmentstructure 840 to left and right arms of armature 3750 to facilitatemechanical coupling thereof. Since attachment structure 840, inparticular mounting protrusion 845 and flexible base 848, is flexible,the HMD device may be capable of accommodating various user crownwidths. For example, in the case of wider user crowns, attachmentstructures 840 may elastically flex distally to provide a comfortablefit. In this way, an HMD device may accommodate wider user crowns, eventhough the armature 3790 may be relatively stiff and rigid in order toprovide strength and support for display assembly 3790. Besidesaccommodating varying head widths, flexible attachment structure 840also accounts for the changing distance between the crown band and thefront housing assembly as the eye relief is adjusted and the fronthousing assembly attach point moves along the side curvature of aspecific user's head. Furthermore, eye relief adjustment may beperformed via timing bands 560, timing band racks 568, side racks 566,and pinions 592 in the timed manner, as described above with referenceto the example embodiments.

Returning to FIG. 37, it illustrates an HMD 3700 comprising armature3750 with display assembly 3790 mounted thereon. Axis 3702 illustratesposterior, anterior, left, right, dorsal, and ventral directions.Armature 3750 is mounted at left and right sides of the HMD device atattachment structures. As described above with reference to the exampleHMD device embodiments, attachment structures may comprise one or moreof attachment structures 140, 540, 640, 740, and 840. HMD 3700 furthercomprises an HMD device including an eye relief rack housing 270 mountedto the adjustable crown band 210, left and right eye relief bands 250,252 wrapped around adjacent to a distal surface of adjustable crown band210 at an anterior side, and housing 230 mounted to adjustable crownband at a posterior side. In this way, HMD device of HMD 3700 mayinclude several features of HMD device 200 including adjusting crowncircumference via housing 230 by rotating a knob 220 rotatably coupledto a crown rack pinion 292 thereat, wherein the crown rack pinion 292may be engaged to crown racks mounted to posterior ends of theadjustable crown band 210. Furthermore, adjusting an eye relief distance3792 of HMD device of HMD 3700 may include applying a pushing force todisplay assembly 3790 toward or applying a pulling force to displayassembly 3790 away from the user's crown to thereby rotate crown rackpinion 292 engaged to eye relief racks 280, 282. Further still, as shownin FIG. 37, HMD device of HMD 3700 may be worn at an angle 545 to theanterior-posterior axis. Furthermore, the attachment structures forattaching armature 3750 to the HMD device of HMD 3700 may be configuredto rigidly support armature 3750 to maintain the angle 545 during use ofthe HMD (e.g., including wearing, and donning and doffing the HMD) andto flexibly support armature 3750 to accommodate various user crownwidths (as in attachment structures 740 and/or 840. By positioningarmature at an angle 545 to adjustable crown band 210, eye reliefdistance may be adjusted substantially linearly aligned with theposterior-anterior axis, even though the adjustable crown band may beworn at an angle 545 above the posterior-anterior axis.

Turning now to FIG. 38, it illustrates an example of a display assembly3790 mounted to an armature 3750. Display assembly 3790 may be mountedat a central mounting position 3810 at an anterior side of armature 3750(e.g., at a distal side of armature 3750 relative to a user's crown). Atproximal surfaces of posterior ends of the armature 3750, couplingstructures 3740 may include openings, cavities, and other structurescomplementary to attachment structures (e.g., one or more of attachmentstructures 140, 540, 640, 740, and 840) for coupling and attachingarmature 3750 to the corresponding HMD device of an HMD. Armature 3750may have an approximately semi-circular arced shape to provide strengthand rigidity to the HMD, while conforming approximately to a shape ofthe user's crown, and to reduce a weight of the HMD. FIG. 39 illustratesan example of the armature 3750.

It will be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated and/ordescribed may be performed in the sequence illustrated and/or described,in other sequences, in parallel, or omitted. Likewise, the order of theabove-described processes may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

The invention claimed is:
 1. A head mounted display (HMD) to be worn bya user, comprising: an adjustable crown band; a crown band circumferenceadjusting mechanism coupled to the adjustable crown band and configuredto adjust a circumference of the crown band to releasably secure thecrown band to the crown of the user; an armature including a left armand a right arm, each of the left arm and the right arm mounted at arespective proximal end to corresponding left and right attachmentstructures on the HMD; a display mounted at left and right sides torespective distal ends of the left and right arms; and an eye reliefdistance adjustment mechanism comprising respective sliding structureson the crown band that slidingly receive the left arm and the right armsuch that the left arm and the right arm can slide in a timed manner tomove the display toward and away from the crown band along asubstantially linear path when a pushing or pulling force is applied tothe display by the user, to thereby adjust an eye relief distance fromthe display to an eye of the user when the crown band is fitted on thecrown of the user.
 2. A head mounted display (HMD) to be worn by a user,comprising: an adjustable crown band; a crown band circumferenceadjusting mechanism coupled to the adjustable crown band and configuredto adjust a circumference of the crown band to releasably secure thecrown band to the crown of the user, the crown band circumferenceadjusting mechanism comprising: a first housing mounted at a posteriorend of the HMD, the first housing including a first knob and a firstpinion rotatably coupled thereto; and left and right crown racks mountedat posterior ends of the adjustable crown band, the left and right crownracks passing through the first housing and engaged to the first pinionwherein rotating the first pinion via the first knob adjusts a length ofthe left and right crown racks passing through the first housing toadjust the circumference of the crown band; an armature including a leftarm and a right arm, each of the left arm and the right arm mounted at arespective proximal end to corresponding left and right attachmentstructures on the HMD; a display mounted at left and right sides torespective distal ends of the left and right arms; and an eye reliefdistance adjustment mechanism configured to move the left and right armsin a timed manner toward and away from the crown band along asubstantially linear path when a pushing or pulling force is applied tothe display by the user, to thereby adjust an eye relief distance fromthe display to an eye of the user when the crown band is fitted on thecrown of the user.
 3. The HMD of claim 2, wherein the eye reliefdistance adjustment mechanism comprises: left and right eye relief bandsincluding the left and right attachment structures, the left and righteye relief bands extending posteriorly from the left and rightattachment structures respectively and passing through the firsthousing, the left and right eye relief bands each including an eyerelief rack engaged to the first pinion, wherein rotating the firstpinion via the first knob adjusts a length of the left and right eyerelief racks passing through the first housing to move the left andright arms in the timed manner.
 4. The HMD of claim 3, wherein the eyerelief distance adjustment mechanism further comprises respectivesliding structures on the crown band that slidingly receive the left armand the right arm such that the left arm and right arm can slide in thetimed manner to move the display toward and away from the crown bandalong the substantially linear path, when the pushing or pulling forceis applied to the display by the user.
 5. The HMD of claim 2, whereinthe eye relief distance adjustment mechanism comprises: a second housingmounted at an anterior end of the HMD, the second housing including asecond knob and a second pinion rotatably coupled thereto; and left andright eye relief bands including the left and right attachmentstructures, the left right eye relief bands extending anteriorly fromthe left and right attachment structures respectively, the left andright eye relief bands each including an anterior eye relief rackengaged to the second pinion mounted, wherein rotating the second pinionvia the second knob moves the left and right eye relief bands in thetimed manner.
 6. The HMD of claim 5, wherein the eye relief distanceadjustment mechanism further comprises respective sliding structures onthe crown band that slidingly receive the left arm and the right armsuch that the left arm and right arm can slide in the timed manner tomove the display toward and away from the crown band along thesubstantially linear path, when the pushing or pulling force is appliedto the display by the user.
 7. The HMD of claim 2, wherein: the firsthousing further includes a second knob and a second pinion rotatablycoupled thereto; and the eye relief distance adjustment mechanismcomprises left and right eye relief bands including the left and rightattachment structures, the left and right eye relief bands extendingposteriorly from the left and right attachment structures respectivelyand passing through the first housing, the left and right eye reliefbands each including an eye relief rack engaged to the second pinion,wherein rotating the second pinion via the second knob adjusts a lengthof the left and right eye relief racks passing through the first housingto move the left and right arms in the timed manner.
 8. The HMD of claim7, wherein the first knob and the second knob are configured in a nestedarrangement, and the first pinion and the second pinion are coaxial. 9.The HMD of claim 7, wherein the eye relief adjustment mechanismcomprises a non-backdrivable eye relief adjustment mechanism to preventadjustment of the eye relief distance without rotation of the first knobor the second knob.
 10. The HMD of claim 2, wherein the eye reliefdistance adjustment mechanism comprises: left and right timing bandsincluding the left and right attachment structures, the left and righttiming bands extending posteriorly from the left and right attachmentstructures respectively and passing through the first housing, the leftand right timing bands each including first left and right eye reliefracks mounted at posterior ends of the left and right timing bands, thefirst left and right eye relief racks engaged to the first pinion,wherein rotating the first pinion via the first knob adjusts a length ofthe first left and first right eye relief racks passing through thefirst housing to move the left and right arms in the timed manner. 11.The HMD of claim 10, wherein the left and right attachment structurescomprise respective left and right pinions, the left and right timingbands comprise second left and second right eye relief racks engaged tothe left and right pinions and mounted at anterior ends of the left andright timing bands, and the eye relief distance adjustment mechanismfurther comprises respective sliding structures mounted on the left andright pinions that slidingly receive the left arm and the right arm suchthat the left arm and right arm can slide in the timed manner to movethe display toward and away from the crown band along the substantiallylinear path, when the pushing or pulling force is applied to the displayby the user.
 12. The HMD of claim 11, wherein the left and right armsextend horizontally anterior from the left and right attachmentstructures, and the adjustable crown band is anteriorly angled upwardsfrom the left and right arms.
 13. The HMD of claim 2, wherein the eyerelief distance adjustment mechanism comprises: a timing band extendinganteriorly from left and right pinions positioned at left and rightattachment structures respectively, the timing band comprising left andright eye relief racks mounted at posterior ends of the timing band andengaged to the left and right pinions, and respective sliding structuresmounted on the left and right pinions that slidingly receive the leftarm and the right arm such that the left arm and right arm can slide inthe timed manner to move the display toward and away from the crown bandalong the substantially linear path, when the pushing or pulling forceis applied to the display by the user.
 14. The HMD of claim 13, whereinthe left and right arms extend horizontally anterior from the left andright attachment structures, and the adjustable crown band extendsanteriorly angled upwards from the left and right arms.
 15. The HMD ofclaim 2, wherein the eye relief distance adjustment mechanism comprises:left and right eye relief bands including the left and right attachmentstructures, the left and right eye relief bands extending posteriorlyfrom the left and right attachment structures respectively and passingthrough the first housing, the left and right eye relief bands eachincluding an eye relief rack engaged to the first pinion, whereinrotating the first pinion via the first knob adjusts a length of theleft and right eye relief racks passing through the first housing tomove the left and right arms in the timed manner.
 16. The HMD of claim15, wherein anterior ends of the left and right eye relief bandsextending anteriorly from the left and right attachment structuresrespectively include ventrally and laterally left and right deformablebands, respective sliding structures mounted on the left and rightdeformable bands that slidingly receive the left arm and the right armsuch that the left arm and right arm can slide in the timed manner tomove the display toward and away from the crown band along thesubstantially linear path, when the pushing or pulling force is appliedto the display by the user.
 17. The HMD of claim 16, wherein the leftand right anterior ends extend horizontally anterior from the left andright attachment structures, and the adjustable crown band extendsanteriorly angled upwards from the left and right arms.
 18. The HMD ofclaim 2, further comprising: a first housing mounted at a posterior endof the HMD, the first housing including a shiftable knob, a staticpinion, and a shiftable pinion; a second housing mounted at an anteriorend of the HMD, the second housing including a timing pinion; first leftand first right crown racks mounted at posterior ends of the adjustablecrown band, the first left and first right crown racks passing throughthe first housing and engageable to the static pinion; second left andsecond right crown racks mounted at anterior ends of the adjustablecrown band, the second left and second right crown racks passing throughthe second housing and engageable to the timing pinion; and a timingband including a posterior crown timing rack and a posterior eye relieftiming rack, each mounted at a posterior end of the timing band andengageable to the shiftable pinion; an anterior crown timing rack and ananterior eye relief timing rack, each mounted at an anterior end of thetiming band and engageable to the timing pinion, wherein the crown bandcircumference adjusting mechanism comprises the shiftable knob shiftedto a first position to engage the first left and first right crown rackswith the static pinion, engage the second left and second right crownracks with the timing pinion, engage the anterior crown timing rack andthe posterior crown timing rack with the timing pinion, and adjust thecircumference of the crown band while maintaining the eye reliefdistance.
 19. The HMD of claim 18, wherein the eye relief distanceadjustment mechanism comprises the shiftable knob shifted to a secondposition to disengage the first left and first right crown racks withthe static pinion, engage the second left and second right crown rackswith the timing pinion, engage the anterior eye relief timing rack andthe posterior eye relief timing rack with the timing pinion, and adjustthe eye relief distance while maintaining the circumference of the crownband.
 20. A head mounted display (HMD) to be worn by a user, comprising:an armature including a left arm and a right arm, each of the left armand the right arm mounted at a respective proximal end to correspondingleft and right attachment structures on the HMD; a display mounted atleft and right sides to respective distal ends of the left and rightarms; and an eye relief distance adjustment mechanism configured to movethe left and right arms in a timed manner toward and away from an eye ofthe user along a substantially linear path when a pushing or pullingforce is applied to the display by the user, to thereby adjust an eyerelief distance from the display to the eye of the user, the eye reliefdistance adjustment mechanism comprising respective linear motionactuators at the left and right attachment structures that slidinglyreceive the left arm and the right arm such that the left arm and theright arm can be linearly slid in the timed manner to move the displaytoward and away from the crown band along the substantially linear path.